South Africa: Analysis – What Climate Change Might Mean for Malaria in SA. Mosquitoes that spread malaria will, and already are, relocate due to global warming. One might anticipate more biting and rapid reproduction from them. Consequently, infectious disease specialists express concern that malaria cases may rise, undermining eradication efforts.
Malaria is now most prevalent in sub-Saharan Africa. Worldwide, the World Health Organization reported 247 million malaria cases each year, leading to 619,000 deaths. Africa accounts for 95% of all cases and 96% of all fatalities from this disease.
According to climate scientist Chris Lennard of the Climate Systems Analysis Group (CSAG) at the University of Cape Town (UCT), temperatures in southern Africa are expected to rise by 1.6°C in the next 20 years, degrees relative to the pre-industrial years (1850 – 1900), with a range of 1.3°C to 2.1°C at the hot end.
He cites the most recent projections from the Intergovernmental Panel on Climate Change for the area, which predict a rise in temperature of between 1.8 and 2.9 degrees Celsius for the decade 2040–2060.
Worldwide, the World Health Organization reported 247 million malaria cases each year, leading to 619,000 deaths.
Temperature and precipitation increases alter the development, behavior, and geographic dispersion of insects like mosquitoes. Climate change makes it easier for malaria mosquito breeding sites to expand, undermining efforts to curb the disease.
South Africa’s Efforts to Combat Malaria
When compared to other nations in the area, South Africa has a far better track record of successfully combating malaria, which may be attributed, at least in part, to the country’s less malaria-friendly environment. Malaria is endemic only in the northeastern portion of the nation, with a small local population. However, when temperatures and precipitation rise in other regions of the nation, there is a chance that malaria cases may climb as well.
Increased rainfall would certainly increase the number of malaria mosquito breeding sites in South Africa, write Shüné Oliver and Jaishree Raman of the National Institute of Communicable Diseases for The Conversation. Heavy spring rains have been linked to increased malaria cases in Limpopo over the summer. Raman told Spotlight that mosquito breeding grounds are destroyed when it floods. On the other hand, Raman warns, “It is the water pools that remain after flooding that are problems as they are the ideal breeding areas for malaria mosquitoes.”
Currently, local transmission of malaria occurs in sections of Mpumalanga and Limpopo, with the former accounting for over 60% of cases and the latter for fewer than 1% of cases. Seasonal patterns in transmission show an increase in cases in October, a peak in January and February, and a decline in cases by May. The province of Gauteng has also had imported cases.
According to Professor Rajendra Maharaj, director of the Malaria Research Unit of the South African Medical Research Council, Malaria mosquitoes mature more rapidly in higher temperatures. The life cycle of a mosquito, from egg to adult, takes roughly 12 summer days and 30 winter days.
The ideal temperature for transmission, as measured by the parasite’s growth within the mosquito, is 26 degrees Celsius, with a minimum of 17 degrees Celsius and a high of 35 degrees Celsius reported in research published in the journal Plos Biology.
According to Maharaj, malaria mosquitos have been seen in unusual locations around South Africa. The cold-blooded mosquito is normally ineffective at higher elevations. They use environmental temperatures to control internal processes, avoiding places where their bodies would be stunted. He argues that Malaria vectors seem to be migrating higher “up the mountains” due to climate change.
In the past, we’ve considered that a certain number of meters above sea level marked the upper limit for mosquito dispersal. Above around 1,000 feet, breeding and survival would be difficult for them. In Kenya, though, we saw insects at much greater heights (on Mount Kilimanjaro). Further, Maharaj adds, “we have seen some mosquito populations far higher up in the mountains in KwaZulu-Natal than we have found there,”
He claims that because of the increased warmth (by “probably a degree warmer”), mosquitoes have migrated to these regions, where they can thrive and multiply.
Another sign that mosquitoes have already begun their annual migration can be seen near Richards Bay. There are no reports of malaria mosquitoes south of the KwaZulu-Natal harbor. The massive breeding populations we see in Richards Bay suggest that “something is afoot,” as Maharaj puts it. The mosquitoes’ aquatic stages (eggs hatch in 48 hours, and larvae and pupae remain in the water for nearly a week) need more nutrients as the temperature rises. To ensure their survival, mosquitoes will naturally congregate around food sources.
Climate change increases malaria risk, as Oliver and Raman illustrate. In 2000, they say, South Africa had a malaria outbreak at the same time as devastating floods hit Mozambique. Malaria cases increased because of the “dramatic increase in available breeding sites,” which enabled the insecticide-resistant mosquito species Anopheles funestus to repopulate KwaZulu-Natal.
According to Maharaj, there were around 13,000 malaria cases in South Africa in 2019. There were 7,000 incidents in 2022 (including more than 3,000 imports). Here’s the kicker, though: “[But] this year, and it’s only half a year, and we have already got 6,000 (over 1,700 imported) cases so far,” adds Maharaj.
He claims that numbers were influenced since many instances of malaria were misdiagnosed as COVID-19 and vice versa because symptoms were similar. The presence of COVID-19 serves as a reminder that malaria is once again a problem. However, he noted that effective control techniques had been implemented, and medications were used to treat malaria, reducing the disease’s prevalence. We are unable to provide an estimate for the total number of instances this year. The graph has seen a few blips since 2019, but they’ve all risen. He claims that the provinces of Mpumalanga and KwaZulu-Natal in South Africa are almost malaria-free but that climate change threatens to thwart their efforts.
According to Raman, the current uptick in instances is attributable to the easing of travel restrictions in early 2022.
Because of COVID laws and the proactive, creative activities of several South African provinces’ malaria control programs, “malaria cases during 2020 and 2021 were significantly lower,” she notes.
Raman warns that malaria eradication might be jeopardized if endemic regions expand and mosquitoes grow more quickly due to climate change. According to her, “current evidence suggests that insecticide-resistant mosquitoes cope better with higher temperatures,” making them a direct threat to malaria eradication efforts.
Another CSAG climate scientist, Lisa van Aardenne, noted that the current malaria season in South Africa only lasts for a few months but might change if temperatures rise.
As a result of its proximity to Mozambique and Zimbabwe, South Africa has several places with a high prevalence of malaria.
She explains that temperature is a key factor in the spread of malaria mosquitoes but that rainfall also acts as a barrier. In some parts of South Africa, the weather is ideal, but the precipitation is too little to make it habitable. As a result, future malaria suitability requires consideration of the complicated relationship between temperature and rainfall.
Climate is just one factor to consider. She also mentioned the movement of individuals from places with high malaria prevalence to those with lower prevalence. As a result of its proximity to Mozambique and Zimbabwe, South Africa has several places with a high prevalence of malaria.
Since malaria-carrying mosquitoes do not care about national borders, even non-endemic areas like Gauteng must contend with the disease thanks to the high volume of travelers passing through the region. The region’s chilly winters prevent mosquitoes from establishing breeding populations in Gauteng. She warns that if management measures aren’t in place in neighboring countries, malaria incidence in South Africa might climb due to increasing migration from locations where the disease is prevalent year-round.
“Malaria cases are still on the low side. We won’t have nearly as large an issue as places like the Democratic Republic of the Congo, where malaria affects around a third of the population. Lucky for us. Although it is an issue, the illness burden here is not nearly as severe as in other countries. According to her, effective monitoring is crucial. We can’t afford to lose focus at this time.
Since malaria-carrying mosquitoes do not care about national borders, even non-endemic areas like Gauteng must contend with the disease thanks to the high volume of travelers passing through the region.
Van Aardenne states a “One Health approach” is necessary when considering malaria. This necessitates a team-based, interdisciplinary strategy for combating malaria and other infectious illnesses, considering the interconnectedness of humans, animals, plants, and the environment.
“It is about how humans interact with the environment,” she explains. I want to know where they are and how they are living. Sometimes, all you need is a city. Since stagnant water near informal settlements might serve as mosquito breeding grounds, any intervention must be implemented at the neighborhood level.
But Lennard from CSAG notes that people will ultimately determine the extent of the temperature rise. The pace of warming can be slowed if we reduce our use of fossil fuels and our carbon dioxide output. However, “increased warming is inevitable” if current trends continue, he warns.
